condition mean min max ZT0-3 8.387326 8.387326 8.387326 ZT4-7 8.40343 8.40343 8.40343 ZT8-11 8.387326 8.387326 8.387326 ZT12-15 9.25459 9.25459 9.25459 ZT16-19 7.845851 7.845851 7.845851 ZT20-23 7.888432 7.888432 7.888432